Optical recording medium including a divided track with basic portion and extension portion

ABSTRACT

A recording medium and manufacturing method thereof, the recording medium comprising a control data area in which control data is prerecorded; and an information data area in which information data is to be recorded. The control data has a basic portion and an extension portion. The basic portion has a length corresponding to the information data.

This is a continuation application of application Ser. No. 10/347,225,filed on Jan. 21, 2003 now U.S. Pat. No. 6,785,220, which is acontinuation application of prior application Ser. No. 09/598,291, filedon Jun. 21, 2000, which issued as U.S. Pat. No. 6,535,477. These twoprior applications are incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an optical recording mediumand a manufacturing method thereof, and more particularly to a userrecordable optical recording medium and a manufacturing method thereofwherein unauthorized recording and reproduction of information data isdisabled.

2. Description of the Related Art

At present, a write-once DVD-R (Digital Versatile Disc—Recordable) hasbeen commercially produced as a user recordable optical recording mediumhaving a recording capacity of several gigabytes (Gbytes), and arewritable DVD-RW (DVD—Rewritable) is under development. In addition, alarge amount of high quality copies can be made without substantialdegradation with the significantly improved performance of such largecapacity digital optical recording media and recording/reproducingapparatus.

FIG. 1 is a diagram showing a layout of a physical sector in a radialdirection of a recording surface on a DVD-RW which is taken as anexample. An information area for recording information data is made upof a lead-in area, a data area, and a lead-out area in this order fromthe starting point of the information area (i.e., starting point of thephysical area) outwardly in the radial direction.

As shown in FIG. 2, the lead-in area contains data for use inreproducing the disc such as a reference code, control data, and so on.A control data region is comprised of 192 ECC (Error Correction Code)blocks. In FIG. 2, ECC blocks within the control data region areindicated using relative sector numbers in a range of 0 to 15. Each ofthe ECC blocks has the same contents. In other words, 192 ECC blockshaving the same contents are recorded in succession. One ECC block iscomprised of 16 sectors in which recorded are physical formatinformation, disc manufacturing information, and contents providerinformation. Thus, data related to the reproduction of such informationdata is recorded in the control data region in the lead-in area uponrecording information data on the disc. Upon reproduction of the disc, areproducing apparatus reads these data to reproduce recorded informationdata such as video data based on the read information. In this way, thedisc is recorded and reproduced.

OBJECT AND SUMMARY OF THE INVENTION

However, with the ability of readily providing a large amount of highquality copies as mentioned above, there has arisen a serious problem inthe development of the copy protection technology for preventingunauthorized or illegal copies of recorded information data such asvideo and audio data, computer programs, and so on.

The present invention has been made in view of the problem mentionedabove, and the object of the invention is to provide an opticalrecording medium and a manufacturing method thereof wherein unauthorizedrecording and reproduction of information data is disabled.

To achieve the object, according to one aspect of the present invention,there is provided an optical recording medium having an information datarecording region including groove tracks and land tracks formed inalternation, each of the groove tracks carrying thereon a sequence ofalternately appearing mark portions and space portions, the sequencerepresenting an information data signal, and the land tracks beingformed with a prepit train including at least one prepit which carriespre-information every predetermined data unit of the groove tracks,wherein at least a portion of the groove tracks comprises a plurality ofgroove portions separated by groove-absent portions in a rotationaldirection of the optical recording medium, each of the mark portions oreach of the space portions includes one of the groove-absent portions.

According to another aspect of the present invention, there is providedan optical recording medium having an information data recording regionincluding groove tracks and land tracks formed in alternation, each ofthe groove tracks carrying thereon a sequence of alternately appearingmark portions and space portions, the sequence representing aninformation data signal, and the land tracks being formed with a prepittrain including at least one prepit which carries pre-information everypredetermined data unit of the groove tracks, wherein at least a portionof the groove tracks comprises a plurality of groove portions separatedby groove-absent portions in a rotational direction of the opticalrecording medium, each of the mark portions or each of the spaceportions includes one of the groove-absent portions, and at least one oftwo groove tracks adjacent to the prepit train has a continuous grooveportion extending at least from a leading end to a trailing end of atleast one prepit included in the prepit train in a rotational directionof the optical recording medium. According to another aspect of thepresent invention, there is provided an optical recording medium havingan information data recording region including groove tracks and landtracks formed in alternation, each of the groove tracks carrying thereona sequence of alternately appearing mark portions and space portions,the sequence representing an information data signal, and the landtracks being formed with a prepit train including at least one prepitwhich carries pre-information every predetermined data unit of thegroove tracks, wherein at least a portion of the groove tracks comprisesa plurality of groove portions separated by groove-absent portions in arotational direction of the optical recording medium, each of the markportions or each of the space portions includes one of the groove-absentportions, and at least one of two groove tracks adjacent to the prepittrain has a continuous groove-absent portion extending at least from aleading end to a trailing end of at least one prepit included in theprepit train in a rotational direction of the optical recording medium.

According to another aspect of the present invention, there is providedan optical recording medium having an information data recording regionincluding groove tracks and land tracks formed in alternation, each ofthe groove tracks carrying thereon a sequence of alternately appearingmark portions and space portions, the sequence representing aninformation data signal, and the land tracks being formed with a prepittrain including at least one prepit which carries pre-information everypredetermined data unit of the groove tracks, wherein at least a portionof the groove tracks comprises a plurality of groove portions separatedby groove-absent portions in a rotational direction of the opticalrecording medium, each of the mark portions or each of the spaceportions includes one of the groove-absent portions, one of two groovetracks adjacent to the prepit train has a continuous groove portionextending at least from a leading end to a trailing end of at least oneprepit included in the prepit train in a rotational direction of theoptical recording medium, and another groove track of the two groovetracks adjacent to the prepit train has a continuous groove-absentportion extending at least from a leading end to a trailing end of atleast one prepit included in the prepit train in a rotational directionof the optical recording medium.

According to further another aspect of the present invention, there isprovided a method of manufacturing an optical recording medium having aninformation data recording region, comprising the steps of forminggroove tracks carrying thereon a sequence of alternately appearing markportions and space portions, the sequence representing an informationdata signal, and forming land tracks, in alternation with the groovetracks, having a prepit train including at least one prepit whichcarries pre-information every predetermined data unit of the groovetracks, wherein the step of forming groove tracks includes a step offorming a plurality of groove portions, at least in a portion of thegroove tracks, separated by groove-absent portions in a rotationaldirection of the optical recording medium, each of the mark portions oreach of the space portions includes one of the groove-absent portions.

According to another aspect of the present invention, there is provideda method of manufacturing an optical recording medium having aninformation data recording region, comprising the steps of forminggroove tracks carrying thereon a sequence of alternately appearing markportions and space portions, the sequence representing an informationdata signal, and forming land tracks, in alternation with the groovetracks, having a prepit train including at least one prepit whichcarries pre-information every predetermined data unit of the groovetracks, wherein the step of forming groove tracks includes a step offorming a plurality of groove portions, at least in a portion of thegroove tracks, separated by groove-absent portions-in a rotationaldirection of the optical recording medium, each of the mark portions oreach of the space portions includes one of the groove-absent portions,and at least one of two groove tracks adjacent to the prepit train has acontinuous groove portion extending at least from a leading end to atrailing end of at least one prepit included in the prepit train in arotational direction of the optical recording medium.

According to further another aspect of the present invention, there isprovided a method of manufacturing an optical recording medium having aninformation data recording region, comprising the steps of forminggroove tracks carrying thereon a sequence of alternately appearing markportions and space portions, the sequence representing an informationdata signal, and forming land tracks, in alternation with the groovetracks, having a prepit train including at least one prepit whichcarries pre-information every predetermined data unit of the groovetracks, wherein the step of forming groove tracks includes a step offorming a plurality of groove portions, at least in a portion of thegroove tracks, separated by groove-absent portions in a rotationaldirection of the optical recording medium, each of the mark portions oreach of the space portions includes one of the groove-absent portions,and at least one of two groove tracks adjacent to the prepit train has acontinuous groove-absent portion extending at least from a leading endto a trailing end of at least one prepit included in the prepit train ina rotational direction of the-optical recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a layout of a physical sector on awrite-once or a rewritable DVD in a radial direction of a recordingsurface;

FIG. 2 is a diagram showing the structure of a lead-in area and acontrol data region;

FIG. 3 is a perspective view illustrating the structure of a controldata region in a conventional DVD-RW;

FIG. 4 is a diagram for illustrating the structure of frames and prepitsin a physical sector;

FIG. 5 is a plan view schematically showing groove tracks and landtracks in a control data section according to the first embodiment ofthe present invention;

FIG. 6 is a plan view schematically showing groove tracks and landtracks in a control data section according to the second embodiment ofthe present invention;

FIG. 7 is a plan view schematically showing groove tracks and landtracks in a control data section according to the third embodiment ofthe present invention;

FIG. 8 is a plan view schematically showing groove tracks and landtracks in a control data section according to the fourth embodiment ofthe present invention;

FIG. 9 is a plan view schematically showing groove tracks and landtracks in a control data section according to the fifth embodiment ofthe present invention;

FIG. 10 is a plan view schematically showing groove tracks and landtracks in a control data section according to the sixth embodiment ofthe present invention;

FIG. 11 schematically shows a configuration of groove tracks and landtracks in a control data section according to the seventh embodiment ofthe present invention; and

FIG. 12 shows a push-pull signal level variation against a length of anextension portion.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Several embodiments of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

FIG. 3 is a perspective view illustrating the structure of a recordingsurface of a conventional recordable optical recording medium, whereDVD-RW is taken as an example.

An optical disc (DVD-RW) 11 is a phase-change-type optical disc on whichinformation data can be rewritten. The optical disc 11 comprises amulti-layer 15 comprised of a recording layer made of a phase changematerial (for example, GeSbTe or the like) as a data recording layer,and glass-based (ZnS—SiO₂) protection layers sandwiching the recordinglayer. The optical disc 11 is formed thereon with groove tracks 12serving as information recording tracks, and land tracks 13 serving asguide tracks for guiding an optical beam (B) such as a laser beam or thelike, which serves as reproducing light or recording light, to thegroove tracks 12. The optical disc 11 further comprises a reflectivelayer 16 for reflecting the light beam (B) for reproducing recordeddata, and an adhesive layer 19 for adhering the overlying layers on atransparent substrate (made of polycarbonate) 18. Further, the opticaldisc 11 is provided with a transparent film (made of polycarbonate) 17for protecting the layers on the side from which the optical beam (B)enters. The land tracks 13 are formed with prepits 14 corresponding topre-information (i.e., previously recorded information). The prepits 14carry pre-information used by an information recording/reproducingapparatus for performing recording and reproduction, i.e., an addressfor recognizing a position on a groove track 12, and synchronizationinformation. The prepits 14 have been preformed before the disc 11 isshipped.

In the optical disc 11, the groove tracks are further wobbled at afrequency corresponding to a disc rotating speed. The wobbled groovetracks 12 have been preformed before the optical disc 11 is shipped, asis the case of the prepits 14.

For recording certain recording information data (hereinafter,“recording information data” refers to information data such as imageinformation which should be essentially recorded on the optical disc 11other than the pre-information) on the optical disc 11, an informationrecording apparatus extracts the wobbling frequency of the groove tracks12 to control the optical disc 11 to rotate at a predetermined rotatingspeed, and detects the prepits 14 to previously acquire thepre-information. Based on the acquired pre-information, the informationrecording apparatus sets an optimal output for the optical beam (B) asrecording light, and so on, and acquires address information of theposition on the optical disc 11 at which the recording information datais to be recorded. Based on the address information, the recordinginformation data is recorded at a corresponding recording position.

Upon recording the recording information data, the optical beam (B) isirradiated such that the center of the optical beam (B) matches thecenter of the groove track 12 to form recording information pitscorresponding to the recording information data on the groove track 12,thereby recording the recording information data. In this event, thesize of a light spot (SP) is set such that a portion thereof isirradiated to the adjacent land tracks 13 as well as the groove track12, as illustrated in FIG. 3.

Portions of the reflected light beam at the light spot (SP) irradiatedto the land tracks 13 are used to detect pre-information from theprepits 14 to acquire the pre-information as well as to extract a wobblesignal from the groove track 12 to acquire a recording clock signalsynchronized with the rotation of the disc, for example, in accordancewith a “radial push-pull method” using a photodetector which is dividedby a division line parallel to the tangential direction of the groovetrack 12 (i.e., the direction in which the optical disc 11 is rotated).

A recording format for the pre-information previously recorded on theoptical disc 11 will now be described with reference to FIG. 4.Specifically, in FIG. 4, the upper part illustrates a recording formatin the recording information data, and the waveforms on the lower partillustrate, as a plan view of the groove track 12, a wobbling state of agroove track 12 on which the recording information data is recorded.Upwardly directed arrows between the recording information data and thewobbling state of the groove track 12 schematically indicate thepositions at which prepits 14 are formed. It should be noted herein thatFIG. 4 shows the wobbling state of the groove track 12 using anamplitude larger than the actual amplitude for facilitating theunderstanding. The recording information data is recorded on the centerline of the groove track 12.

As illustrated in FIG. 4, the recording information data to be recordedon the optical disc 11 has been previously divided into sync frames asinformation units. Then, one recording sector is formed of 26 syncframes, and one ECC block is formed of 16 recording sectors.Specifically, one sync frame has a length 1,488 times longer than achannel bit length (hereinafter denoted by “T”) defined by the recordingformat which is used for recording the recording information data (i.e.,1,488T). Further, a portion extending over the length of 32T at the headof each sync frame is used as synchronization information SY forestablishing the synchronization for each sync frame.

The pre-information recorded on the optical disc 11, on the other hand,is recorded in each sync frame. Here, when the pre-information isrecorded on the optical disc 11 in the form of prepits 14, one prepit 14is formed for indicating a synchronization signal in the pre-informationon a land track 13 adjacent to a region in which synchronizationinformation SY is recorded in the respective sync frames in therecording information. Also, two or one prepit 14 is formed forindicating the contents of the pre-information to be recorded, on a landtrack 13 adjacent to the former half portion of the sync frame otherthan the synchronization information SY. As to the former half portionof the sync frame other than the synchronization information SY, theprepit 14 may not be formed depending on the contents of pre-informationto be recorded. In this event, prepits 14 are generally formed only ineven-numbered sync frames (hereinafter, referred to as “EVEN frames”) torecord pre-information. The exceptions will be described later.Specifically, in FIG. 4, the prepits 14 are formed in the EVEN frames(indicated by solid upwardly directed arrows in FIG. 4), whereas noprepits 14 are formed in odd-numbered frames adjacent thereto(hereinafter, referred to as “ODD frames”). More specifically, whenprepits are formed in an EVEN frame, all prepits 14 (i.e., prepits B2,B1, B0 which are labeled in this order from the head of the sync frame)are formed in the first sync frame in a recording sector, and prepitsB2, B0 are formed in a sync frame other than the first one in therecording sector when pre-information to be recorded in the sync frameis “1,” and only a prepit B2 is formed when pre-information to berecorded is “0.” Also, when prepits are formed in an ODD frame, prepitsB2, B1 are formed in the first sync frame of a recording sector. In syncframes other than the first one in the recording sector, prepits areformed in a manner similar to those in the EVEN frame. Stated anotherway, the prepits 14 have different meanings in accordance with thevarying prepit train of B2, B1 and B0.

Whether the prepits 14 are formed in the sync frame of the EVEN frame orthe ODD frame is determined in accordance with the position of a prepit14 previously formed on an adjacent land track. More specifically, whilethe prepits 14 are generally formed in the EVEN frame, if the prepitsformed in the EVEN frame are located close to previously formed prepits14 on an adjacent land track in the radial direction of the disc, theprepits 14 are formed in the ODD frame. By thus forming the prepits 14,the influence of crosstalk can be reduced when the prepits 14 aredetected because no prepit 14 exists on an adjacent land track position.

The groove track 12, on the other hand, is wobbled at a constantwobbling frequency f0 of 140 kHz (i.e., a frequency at which eightcycles of wobble signal is contained in one sync frame) over the entiresync frame. Then, an information recording apparatus extracts theconstant wobbling frequency f0 to detect a signal for controlling aspindle motor for rotating the disc, and to generate a recording clocksignal.

A first embodiment of the present invention will be described in detail.FIG. 5 is a plan view schematically showing groove tracks 12 and landtracks 13 in a control data section in a lead-in area.

The groove tracks 12 are formed as intermittent groove tracks separatedby portions of the same depth as the land tracks 13 (on the same plane),i.e., groove-absent portions, except for a neighborhood of a prepittrain formed of three prepits 14A, 14B, 14C. The groove tracks 12 arecreated, for example, by 8/16 modulating a cutting light beam andturning ON/OFF the emitting power (with a duty ratio of approximately50%) during the groove cutting. In other words, the groove tracks 12have an intermittent structure, in which the groove tracks are dividedbased on a signal having the same frequency band as a recording RFsignal (i.e., a recording signal after 8/16 modulated) recorded on theoptical disc. It can be said that this structure is such that thelengths of each groove portion and groove-absent portion (hereinafter,referred to as the “mirror portion”) correspond to the length of a pitand the interval between pits formed during information recording. Eachof the groove portions corresponds to a mark (or a space) of theinformation data.

On a track traced for reading the prepits 14A, 14B, 14C, a continuousgroove 12A adjacent to an entire area occupied by at least the prepits14A, 14B, 14C is formed in a sync frame that includes these prepits. Inother words, the groove 12A is formed as a continuous groove whichextends at least from the leading end of the prepit train (i.e., theleading end of the prepit 14A) to the trailing end of the prepit train(i.e., the trailing end of the prepit 14C) in the tracking direction.Also, in the embodiment, another continuous groove 12B adjacent to theprepits 14A, 14B, 14C is formed on the opposite side of the continuousgroove 12A beyond the prepits 14A, 14B, 14C.

When some 8/16 modulated information is recorded on the foregoingintermittent groove tracks having the structure described above and thenreproduced, an RF signal reproduced from the intermittent groove trackshas an amplitude too small to read except for the region of the groove12A. This is because the frequency due to the intermittence (i.e.,ON-OFF) of groove tracks is in a frequency band equivalent to therecorded RF signal so that they interfere with each other. On the otherhand, a pre-information signal can be read because the continuousgrooves 12A, 12B do not cause such interference of the signals in aregion in which the prepits 14A, 14B, 14C are formed. Also, in theregion of the groove 12A, additional control signals such as a trackingerror signal and a wobble signal other than the prepit signal must beread. As described above, since the groove portions exist in a dutyratio of approximately 50% in the intermittent groove tracks, thepush-pull tracking error signal and the wobble signal have levelsapproximately one-half of those in the continuous grooves, but can servesufficiently for tracking control.

Thus, by intermittently forming the groove tracks in the control datasection of the lead-in area, except for a region adjacent to theprepits, even if control data is recorded in the control data section, areproduced RF signal recovered from this portion exhibits a very lowlevel, and consequently the control data cannot be reproduced. In otherwords, recording information data such as image information and so on,which should be essentially recorded and reproduced, cannot bereproduced, thereby making it possible to prevent unauthorized copies.However, for properly copying information data on the recording mediumof the embodiment, a variety of techniques for avoiding the copyprotection may be implemented in either hardware or software such as anavoiding apparatus, a computer program, and so on.

A second embodiment of the present invention will be described indetail. FIG. 6 is a plan view schematically showing groove tracks 12 andland tracks 13 in a control data section in a lead-in area.

The second embodiment differs from the first embodiment in that a regionadjacent to an entire area including prepits 14A, 14B, 14C is formed asa continuous mirror portion 22A on a track which is traced for readingthe prepits 14A, 14B, 14C. More specifically, the mirror portion 22A isformed continuously at least from the leading end of the prepit 14A tothe trailing end of the prepit 14C in the tracking direction. Also, inthe second embodiment, another mirror portion 22B adjacent to theprepits 14A, 14B, 14C is formed opposite to the mirror portion 22Abeyond the prepits 14A, 14B, 14C.

Thus, like the first embodiment, the foregoing structure prevents areproduced RF signal from being read from the intermittent groove tracksin the recording region due to the interference of the intermittence ofthe groove tracks themselves with the recorded RF signal. On the otherhand, pre-information can be read by the continuous mirror portions 22A,22B in the regions adjacent to the prepits 14A, 14B, 14C.

It will be apparent that the continuous grooves of the first embodimentand the continuous mirror portions of the second embodiment may be usedin combination. For example, a track traced for reading the prepits 14A,14B, 14C may be formed with a continuous groove 12A adjacent to anentire area including at least the prepits 14A, 14B, 14C, while a mirrorportion 22B may be formed so as to adjoin the prepits 14A, 14B, 14C onthe side opposite to the continuous groove 12A beyond the prepits 14A,14B, 14C.

A third and a fourth embodiment of the present invention will now bedescribed with reference to FIGS. 7 and 8, respectively. FIGS. 7 and 8are plan views schematically showing groove tracks 12 and land tracks 13in a control data section in a lead-in area.

As can be seen from FIG. 7, the third embodiment differs from theaforementioned embodiments in that a continuous groove 12A adjacent toan entire area including at least prepits 14A, 14B, 14C is formed onlyon a track traced for reading the prepits 14A, 14B, 14C. Likewise, inthis structure, pre-information can be read from this section since theinterference of signals is avoided by the continuous groove 12A.

FIG. 8 in turn shows an example in which two prepits 14 are formed insync frames other than the first one in a recording sector (i.e.,prepits B2, B0 or prepits B2, B1). In the fourth embodiment, acontinuous mirror portion 22A is formed instead of the continuous groove12A, in which case similar effects to those of the foregoing thirdembodiment can be produced.

A fifth and a sixth embodiment of the present invention will bedescribed with reference to FIGS. 9 and 10, respectively. The fifth andsixth embodiments differ from the foregoing embodiments in that only oneprepit 14A is formed. Even with these embodiments, a track traced forreading the prepit 14A is formed with a continuous groove 12A (FIG. 9)or a continuous mirror portion 22A (FIG. 10) adjacent to an entire areaincluding at least the prepit 14A, i.e., extending continuously from theleading end to the trailing end of the prepit 14A in the trackingdirection, to avoid the interference of signals, thereby making itpossible to read pre-information.

A seventh embodiment of the present invention will now be described. Asshown in FIG. 11, a control data section in the lead-in area containsgroove tracks 12 and land tracks 13. The groove tracks 12 are dividedinto a plurality of groove portions 12C by mirror portions 22C.

In the embodiment, each of the groove portions 12C is comprised of abasic pit portion 31 and an extension portion (i.e., a groove-presentportion) 32. The basic pit portion 31 has a pit length according to amark (or a space) of the information data. For example, when 8/16modulation is employed, in which 8-bit data is converted to 16channel-bit data, a minimum pit length is 3T and a maximum pit length is11T. As mentioned previously, T is a channel bit length. The maximum pitlength is 14T when sync-pattern of 14T pit-length is used.

When forming the groove tracks 12 by dividing into a plurality of grooveportions 12C, the duty ratio for all of the basic pit portions 31 in thegroove tracks 12 is determined to be approximately 50%. Furthermore, inthe embodiment, the groove portion 12C is comprised of a basic pitportion 31, and an extension portion 32 of a predetermined length. Theextension portion 32 is added to the basic pit portions 31, in order toimprove the detected signal level in a push-pull method (hereinafter,simply referred to as a push-pull signal level).

FIG. 12 shows a variation of push-pull signal level vs the length of theextension portion 32. The push-pull signal level is 0.142 when theextension portion 32 is not added. The push-pull signal level isincreased as the length of the extension portion 32 is increased. Thepush-pull signal level of 0.233 is achieved, which is sufficient fortracking, when the length of the extension portion 32 is set to be 3T.There is, however, a trade-off that an effect to prevent an unauthorizedrecording and reproduction of information data is decreased.

It should be noted that the length of the extension portion 32 and theduty ratio of the basic pit portions 31 can be modified in considerationof, for example, the detected signal level. The length of the extensionportion 32 is not limited to a fixed length as presented in theabove-mentioned embodiment. The length of the extension portion 32 maybe determined in accordance with a length of the succeeding mirrorportion. For example, the extension portion added to a basic pit portionmay have a length proportional to a length of the mirror portionsucceeding to the basic pit portion. The prepits described in the firstthrough sixth embodiments can be provided.

Thus, according to the present invention, unauthorized recording andreproduction can be effectively prevented while the push-pull signallevel, hence the tracking performance is improved by providing theextension portion 32 of a predetermined length to the basic pit portions31.

It should also be noted that the continuous groove, continuous mirrorportion, and so on shown in the foregoing embodiments may be used incombination as appropriate.

Also, while the foregoing embodiments have been described for an examplein which the groove track 12 is divided according to a signal in thesame band as an RF signal recorded on an optical disc, the groove track12 may be divided according to a signal including a portion of a band ofa recorded RF signal.

Further, while the foregoing embodiments have been described inconnection with the DVD-RW which is taken as an example of an opticalrecording medium, the present invention is not limited to the particularrecording medium, but may applied to other optical recording media, forexample, DVD-R or the like.

As will be apparent from the foregoing, according to the presentinvention, the groove tracks are intermittently formed in a control datasection of a lead-in area except for regions adjacent to prepits todisable the reproduction of control data, even if they are recorded inthe control data section, thereby making it possible to realize anoptical recording medium which can prevent unauthorized copies ofrecorded information data. Moreover, not limited to the control datasection of the lead-in area, a recorded signal can be prohibited frombeing read from any arbitrary portion of an optical disc by providingthe intermittent track grooves according to the present invention insuch portion.

The invention has been described with reference to the preferredembodiments thereof. It should be understood by those skilled in the artthat a variety of alterations and modifications may be made from theembodiments described above. It is therefore contemplated that theappended claims encompass all such alterations and modifications.

1. A recording medium comprising: a control data area in which controldata is prerecorded; and an information data area in which informationdata is to be recorded, wherein a groove track of the control data areais divided into a plurality of groove portions by groove-absentportions, the groove portions including a basic pit portion and anextension portion, and wherein the basic pit portion has a pit lengthcorresponding to either one of a mark and a space of the informationdata.
 2. The recording medium according to claim 1, wherein theinformation data area includes a groove track on which the informationdata is to be recorded.
 3. The recording medium according to claim 1,wherein the control data is prerecorded as an alley of groove portionsand groove absent portions.
 4. The recording medium according to claim3, wherein the alley of groove portions and groove absent portions iswobbled.
 5. The recording medium according to claim 1, wherein thecontrol data area comprises a plurality of ECC (Error Correction Code)blocks, each of which includes physical format information.
 6. Therecording medium according to claim 1, wherein the control data area islocated in a lead-in area of the recording medium.
 7. A method ofmanufacturing an optical recording medium on which information data isto be recorded, comprising: recording a control data to form a controldata area; and forming an information data area in which the informationdata is to be recorded, wherein a groove track of the control data areais divided into a plurality of groove portions by groove-absentportions, the groove portions including a basic pit portion and anextension portion, and wherein the basic pit portion has a pit lengthcorresponding to either one of a mark and a space of the informationdata.
 8. The method according to claim 7, wherein forming an informationdata area includes forming a groove track on which the information datais to be recorded.
 9. The method according to claim 7, wherein thecontrol data is prerecorded as an alley of groove portions and grooveabsent portions.
 10. The method according to claim 9, wherein the alleyof groove portions and groove absent portions is wobbled.
 11. The methodaccording to claim 7, wherein the control data area comprises aplurality of ECC (Error Correction Code) blocks, each of which includesphysical format information.
 12. The method according to claim 7,wherein the control data area is formed in a lead-in area of therecording medium.
 13. The recording medium according to claim 1, whereinthe extension portion has a predetermined length.
 14. The recordingmedium according to claim 1, wherein the length of the extension portionis determined in accordance with a length of the groove-absent portionsucceeding to the extension portion.
 15. The recording medium accordingto claim 1, wherein the length of the extension portion is proportionalto a length of the groove-absent portion succeeding to the extensionportion.
 16. The method according to claim 7, wherein the extensionportion has a predetermined length.
 17. The method according to claim 7,wherein the length of the extension portion is determined in accordancewith a length of the groove-absent portion succeeding to the extensionportion.
 18. The method according to claim 7, wherein the length of theextension portion is proportional to a length of the groove-absentportion succeeding to the extension portion.